Aspects of the present invention relate to an engine arrangement and a method for heating exhaust after treatment equipment in an exhaust after treatment system
Diesel engines are often provided with exhaust after treatment equipment to satisfy various environmental regulations. The aftertreatment equipment may comprise lone devices but is more typically part of a larger exhaust after treatment system (EATS) of the type that typically comprises a plurality of different components, such as a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF) which may include a catalyst, and a selective catalytic reduction catalyst (SCR). Ordinarily, each of the components of the EATS has an optimal operating temperature range, such as a range at which any catalyst associated with the component performs optimally, and some components do not perform their intended functions below particular temperatures. Particularly during start-up of the engine or during operation in cold weather, the engine and the exhaust after treatment equipment are at temperatures below the optimal operating temperatures, and may be operated at temperatures so low as to damage the equipment. To avoid damage, it may be necessary to bypass components of the EATS. If the EATS components are not operating optimally or are bypassed, it may not be possible for the engine arrangement to attain desired emissions levels. Additionally, it is periodically necessary to regenerate certain EATS components, such as DPFs and SCRs, at higher temperatures than are typically encountered under normal operating conditions. There are presently a number of different arrangements and techniques for more rapidly increasing heating of EATS components and/or generally increasing temperatures of EATS components to provide a “heat mode” such as via use of such devices as variable geometry turbochargers, intake throttles on diesel engines, exhaust restricting devices such as flappers and butterfly valves, and introducing fuel into the exhaust combined with a diesel oxidation catalyst, and/or exhaust burner devices. Many of these structures for providing a heat mode only function to assist in providing the heat mode and do little or nothing else. It is desirable to provide additional arrangements and techniques to supplement or replace existing arrangements and techniques for raising temperature of EATS components to minimal or optimal operating ranges and/or for purposes of regeneration. It is also desirable to minimize the size of the arrangement for providing a heat mode.
An engine arrangement according to an aspect of the present invention comprises an engine, an exhaust line connected downstream of the engine, exhaust after treatment equipment in the exhaust line, a temperature sensor for sensing a temperature of the exhaust after treatment equipment, and a turbo compound arrangement including a turbo compound turbine in the exhaust line and means for modifying exhaust flow through the turbo compound arrangement and the exhaust line in response to one or more temperature sensor signals.
In accordance with another aspect of the invention, a method is provided for heating exhaust after treatment equipment in an exhaust after treatment system (EATS) for an engine. The method comprises exhausting gas from the engine into an exhaust line downstream of the engine, the exhaust line including the exhaust after treatment system including the exhaust after treatment equipment, the exhaust line further including a turbo compound arrangement including a turbo compound turbine, sensing temperature of the exhaust after treatment equipment, and modifying exhaust gas flow through the turbo compound arrangement in response to one or more temperature sensor signals.